Born in Bergen, the youngest son of a high-ranking police officer, Ofstad passed the examen artium in 1939 and completed a degree in law in 1945 before changing to philosophy, which he studied under Arne Næss; he was part of the "Bergen group"[1] and one of the most prominent exponents of Næss' "empirical semantics" approach.
He married Erna Magnussen, a historian of literature, in 1945, and published a collection of essays with her in 1961.
[1] Ofstad's interest in philosophy arose out of his encounter with Nazism during World War II, when Norway was occupied by Nazi Germany.
[1][3][4] Like many of his generation, influenced by American social scientists and such thinkers as Theodor W. Adorno, he sought the origins of authoritarianism and nationalism.
[1] He was one of the most cited Norwegian moral philosophers and participated actively in the public debate in both Norway and Sweden; in 1978 he forcefully disagreed with Thorkild Hansen over the latter's book Processen mod Hamsun in a debate televised on NRK.